Even as a pastor (called to answer the door at any hour??), I have done at least one of the above. Which one, I'll never tell...
Here in Cayman, usually around this time of year and again in the Spring is open season for Jehovah's Witnesses to come 'round & lovingly pound at your door. Usually very kind, eager to start a conversation, and unwaveringly convinced of their views about something absolutely foundational to our faith as Christians: The deity of Jesus Christ.
What they are saying. Jehovah's Witnesses are convinced that there is one God -- and Jesus Christ is not Him. One of the first evidences out of their mouth: "Even the Bible (yes, your Bible) says that Jesus Christ was a created being."
They center this around verses like Colossians 1:15: "He [Christ] is the image of the invisible God, the firstborn of all creation." On the surface, this may throw us for a loop -- at the very least, stopping the conversation and, at the very most, planting seeds of doubt in our own minds.
Though you may prefer to just walk away or just say, "Ah well, they'll never change their minds," remember that the true gospel is inherently powerful (Romans 1:16) and many Jehovah's Witnesses are bringing along new (and perhaps still 'open') converts for observation. So perhaps it's worth a little time, effort, and brainpower...
How we might respond. The following is a good blog post that will help us address the claim by Jehovah's Witnesses that the Bible says Jesus Christ is not God but a created being like you and I.
The Deity of Christ - Part III (See his other posts on topic as well)
Before you actually respond. Having said this, I would exhort each of us to recall that the power of the gospel is best demonstrated through loving our neighbor as Christ has so loved us - even in the midst of discussion/debate. I remember once talking to a brother who was a renown apologist for a pro-life stance toward unborn children. His job, at which he was quite accomplished, was engaging in dozens of public forums each year against the the best & brightest pro-choice philosophers & scientists. I asked him, "How often do you feel like you 'lose' debates?" He replied: Some of the debates that on the surface I seemed to win - made the most salient arguments and stumped the opposition - I had in fact lost." He went on to quote 1 Peter 3:15 with an emphasis on the last part of the verse:
"But in your hearts set apart Christ as Lord. Always be prepared to give an answer to everyone who asks you to give you the reason for the hope that you have, but do so with gentleness and respect."An approach I've found helpful is offering to listen for 20-30 minutes and then (either at that or inviting them to return again) ask if they'd be willing to listen to your thoughts & concerns for 20-30 minutes. I did this with some Mormon folks once and we struck up quite a relationship - two of the dudes even asked for some of 'my' literature.